The Devonian batholiths of western Tasmania represent a diverse assemblage of highly fractionated intrusions (70 to 77 percent SiO₂) that are the products of different source materials. The Housetop batholith exhibits compositional affinities to a fluorine-rich I-type magma. The Meredith batholith also has characteristics indicative of I-type source materials. The Heemskirk batholith is composite, and consists of a volatile (F, B, H₂O)–rich S-type granite underlying an I-type granite. The Three Hummock Island, Interview River, Sandy Cape, and Conical Rocks plutons probably have an S-type source and are grouped together as the Sandy Cape Suite. Rapakivi texture...